From eed2dfdc38891432709aaba8ed96e175400ae84e Mon Sep 17 00:00:00 2001
From: Heinz Mauelshagen <heinzm@redhat.com>
Date: Wed, 23 Jan 2013 13:28:00 +0100
Subject: [PATCH] buffer_t.cc: more tests

---
 persistent-data/block.h  |  6 ++--
 persistent-data/buffer.h | 63 +++++++++++++++-------------------------
 unit-tests/Makefile.in   |  4 +++
 3 files changed, 32 insertions(+), 41 deletions(-)

diff --git a/persistent-data/block.h b/persistent-data/block.h
index dbdb32d..44e8606 100644
--- a/persistent-data/block.h
+++ b/persistent-data/block.h
@@ -31,12 +31,14 @@
 #include <boost/optional.hpp>
 #include <boost/shared_ptr.hpp>
 
-#include <string.h>
-#include <malloc.h>
+#include <string>
 
 //----------------------------------------------------------------
 
 namespace persistent_data {
+
+	uint32_t const MD_BLOCK_SIZE = 4096;
+
 	typedef uint64_t block_address;
 
 	template <uint32_t BlockSize = MD_BLOCK_SIZE>
diff --git a/persistent-data/buffer.h b/persistent-data/buffer.h
index 82c4393..437f412 100644
--- a/persistent-data/buffer.h
+++ b/persistent-data/buffer.h
@@ -20,60 +20,40 @@
 #define BUFFER_H
 
 #include <stdint.h>
-#include <stdlib.h>
+// #include <stdlib.h>
+#include <malloc.h>
+
+#include <boost/noncopyable.hpp>
+#include <boost/optional.hpp>
+#include <boost/shared_ptr.hpp>
 
 #include <stdexcept>
-#include <boost/noncopyable.hpp>
 
 //----------------------------------------------------------------
 
 namespace persistent_data {
+	uint32_t const DEFAULT_BUFFER_SIZE = 4096;
 
-	uint32_t const MD_BLOCK_SIZE = 4096;
-
-	// Allocate buffer
+	// Allocate buffer of Size with Alignment imposed.
 	//
 	// Allocation needs to be on the heap in order to provide alignment guarantees!
 	// 
-	// Alignment must be a power of two and a multiple of sizeof(void *)
+	// Alignment must be a power of two.
 
-
-	// Heinz: could you move this to a separate file.  Add a big
-	// comment explaining that you should allocate it on the heap if
-	// you want the alignment guarantees.  Then write a test suite
-	// (buffer_t) that covers the following cases.
-	//
-	// - Allocate several on the heap, check they have the requested
-	//   alignment.  Try for various Alignments.  If memalign has
-	//   restrictions could you document (eg, power of 2).
-
-	// - you can use the [] to set a value in a non-const instance
-
-	// - you can't use the [] to set a value in a const instance - not
-	//   sure how to do this, since it'll be a compile time error.
-
-	// - you can use [] to read back a value that you've set.
-
-	// - [] to read works in a const instance.
-
-	// - you can use raw() to get and set values.
-
-	// - an exception is thrown if you put too large an index in []
-
-	// - check you can't copy a buffer via a copy constructor or ==
-	// - (again a compile time error, just experiment so you understand
-	// - boost::noncopyable).
-
-	template <uint32_t BlockSize = MD_BLOCK_SIZE, uint32_t Alignment = 512>
+	template <uint32_t Size = DEFAULT_BUFFER_SIZE, uint32_t Alignment = 512>
 	class buffer : private boost::noncopyable {
 	public:
+		typedef boost::shared_ptr<buffer> ptr;
+
 		unsigned char &operator[](unsigned index) {
 			check_index(index);
+
 			return data_[index];
 		}
 
 		unsigned char const &operator[](unsigned index) const {
 			check_index(index);
+
 			return data_[index];
 		}
 
@@ -86,20 +66,25 @@ namespace persistent_data {
 		}
 
 		static void *operator new(size_t s) {
-			void *r;
+			// void *r;
+			// return posix_memalign(&r, Alignment, s) ? NULL : r;
 
-			return ::posix_memalign(&r, Alignment, s) ? r : (void*) NULL;
+			// Allocates size bytes and returns a pointer to the
+			// allocated memory. The memory address will be a
+			// multiple of 'Alignment', which must be a power of two
+			return memalign(Alignment, s);
 		}
 
 		static void operator delete(void *p) {
 			free(p);
 		}
 
-	private:
-		unsigned char data_[BlockSize];
+	protected:
+		unsigned char data_[Size];
 
+	private:
 		static void check_index(unsigned index) {
-			if (index >= BlockSize)
+			if (index >= Size)
 				throw std::runtime_error("buffer index out of bounds");
 		}
 
diff --git a/unit-tests/Makefile.in b/unit-tests/Makefile.in
index a1245be..6d7e377 100644
--- a/unit-tests/Makefile.in
+++ b/unit-tests/Makefile.in
@@ -17,6 +17,7 @@
 # <http://www.gnu.org/licenses/>.
 
 TEST_SOURCE=\
+	unit-tests/buffer_t.cc \
 	unit-tests/cache_t.cc \
 	unit-tests/block_t.cc \
 	unit-tests/btree_t.cc \
@@ -31,6 +32,9 @@ unit-test: $(TEST_PROGRAMS)
 
 .PHONY: unit-test
 
+unit-tests/buffer_t: unit-tests/buffer_t.o $(OBJECTS)
+	g++ $(CXXFLAGS) $(INCLUDES) -o $@ $+ $(LIBS) $(LIBEXPAT)
+
 unit-tests/block_t: unit-tests/block_t.o $(OBJECTS)
 	g++ $(CXXFLAGS) $(INCLUDES) -o $@ $+ $(LIBS) $(LIBEXPAT)